The mental health field is currently faced with the challenge of reducing the prevalence of antisocial behavior in children. Children with conduct and oppositional defiant disorders require a substantial effort for remediation. Longitudinal research indicates that increased antisocial behavior and impairments in social competence skills often serve as harbingers of future adjustment problems in a number of domains including mental health, interpersonal relations, employment, and academic achievement. Longitudinal studies of the progression of antisocial behavior patterns among youth in the U.S., Canada, Australia, New Zealand and Europe converge in showing a path leading from early exposure to risk factors in family, neighborhood and community contexts, to behavioral manifestations in school, to delinquency and school dropout in adolescence, and finally to a host of adult adjustment problems including welfare dependence, criminality, marital difficulties, employment problems and higher hospitalization-mortality rates. It is critical to divert at-risk children from this path as soon as possible in their lives and school careers through early, coordinated interventions involving parents and caregivers, teachers and peers. Preschool (e.g. Head Start) is an ideal setting for accomplishing this task in collaboration with families. This application outlines five years of research and development activities that will adapt and assess the efficacy of the First Step to Success early intervention program for effective use with early childhood programs serving low-income children (e.g., Head Start). First Step is a collaborative home and school intervention program, delivered by a behavioral coach and lasting approximately three months, that is geared for regular kindergarten classroom settings and designed to help at-risk children get off to the best start possible in their school careers. First Step is an early intervention designed to achieve secondary prevention goals and outcomes within the context of schooling. The adapted version of the First Step program would provide Head Start consumers, staff and professionals with a proven intervention option that will produce the following benefits: 1) amelioration and/or elimination of serious behavior problems such as aggression, opposition- defiance, and other indicators of emerging antisocial behavior and externalizing behavior disorders, 2) substantially improved school readiness, and 3) improvements in the target child's critically important relationships with the key social agents of parents and caregivers, teachers and peers. PUBLIC HEALTH RELEVANCE: This application outlines five years of research and development activities that will adapt and assess the efficacy of the First Step to Success early intervention program for effective use with early childhood programs, such as Head Start. This preschool version of the First Step program would provide Head Start consumers, staff and professionals with a proven intervention option that will produce the following benefits: 1) amelioration and/or elimination of serious behavior problems such as aggression, opposition- defiance, and other indicators of emerging antisocial behavior and externalizing behavior disorders, 2) substantially improved school readiness, and 3) improvements in the target child's critically important relationships with the key social agents of parents and caregivers, teachers and peers.